Nanoinprint technology has been expected as a lithography method that does not require the use of an expensive exposure device, and focused as a novel micro-processing method for fine processing in manufacture of a semiconductor integrated circuit and a novel micro-processing method for producing a next-generation optical disc.
For forming a fine pattern by nanoinprint, there are the following methods: a method including pressing a mold serving as a mold form for three-dimensional pattern onto thermally plasticized resin to shape the resin, followed by cooling to obtain a three-dimensional resin pattern; and a method including applying an optically curable resin solution on a process substrate and irradiating light on the substrate in a state of being pressed by the mold to obtain an optically cured three dimensional resin pattern. In any of these methods, the processing accuracy of a mold provided as an original edition is important just as in the case with processing accuracy required for a photomask in optical lithography.
Examples a substrate used for producing a mold include a quartz substrate, a silicon substrate subjected to film-formation of a silicon oxide film, a silicon substrate, and a silicon carbide substrate. In particular, among them, the quartz substrate is also usefully employed in optical imprint and thermal inprint.
On the other hand, in an optical lithographic technique as a technique for processing a quartz substrate with high precision, a Levenson type mask has been already used in the production. In the case of carrying out the production of such a mask, a quartz substrate is processed by fluorine-containing dry etching using as a hard mask film a chromium-containing film, which is also used as a light-shielding film and has high etching resistance to fluorine-containing dry etching.
This processing technique can be directly applied to a method for manufacturing a mold. For example, JP 2011-207163 A (Patent Literature 1) proposes a mold production substrate in which a chromium-oxide-nitride-carbide film, which has been used as a light-shielding material in a photomask, is provided as a hard mask film. In addition, there is proposed a substrate for production of a mold having a chromium-containing material layer on the surface side thereof and a tantalum-containing material layer on the substrate side thereof (JP 2009-206338 A: Patent Literature 2).